Magnetically retrievable Bi2WO6/Fe3O4 immobilized on graphene sand composite for investigation of photocatalytic mineralization of oxytetracycline and ampicillin

Supported photocatalysis is emerging as an effective technology to overcome the inherent drawback of metallic photocatalyst. In the present work, heterojunctioned Bi2WO6/Fe3O4 was synthesized by hydrothermal method. Bi2WO6/Fe3O4 was supported over graphene sand composite (GSC) by in situ wet impregnation method to report Bi2WO6/Fe3O4/GSC nanocomposite. The morphological and compositional characteristics of prepared Bi2WO6/Fe3O4/GSC nanocomposite were explored by FESEM, TEM, HRTEM, FTIR, XRD, EDX and UV-vis spectral analysis. The photocatalytic efficiency of synthesized Bi2WO6/Fe3O4/GSC composites was evaluated for mineralization of oxytetracycline (OTC) and ampicillin (AMP) under solar light. The adsorption of both OTC and AMP onto Bi2WO6/Fe3O4/GSC followed pseudo second order kinetics. The synergistic adsorption and photocatalysis (A + P) was most efficient process for oxytetracycline and ampicillin removal and resulted in higher degradation of antibiotics. During A+P process, OTC and AMP were mineralized to CO2, H2O and NO3- ions. Power law model was applied to explore the kinetics of mineralization process. The super paramagnetic nature of photocatalyst was revealed by hysteresis curve. Bi2WO6/Fe3O4/GSC nanocomposite displayed improved adsorption capacity and easy separation from reaction mixture with significant recycle efficiency for 10 successive catalytic cycles. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.